It may be desirable to enable Direct-to-Earth (DTE) and Direct-from-Earth (DFE) links between, for example, Landers or Rovers and the Deep Space Network antennas, rather than relaying signals via a nearby spacecraft. Removing requirement for such nearby spacecraft can significantly reduce the cost of a mission, such as, for example, on Jupiter's icy moons. Based on currently known designs, such DTE and/or DFE links can require a large antenna aperture and a high transmitter power of at least 100 W. Such antenna must operate well at both an uplink frequency (e.g. 7.145-7.190 GHz) and a downlink frequency (e.g. 8.40-8.45 GHz) of for example, the Deep Space frequency bands, and must handle up to 100 W of input power in a vacuum.
Moreover, such antenna must operate well in harsh environment conditions, such as for example, Jupiter's icy moons environment which can present extreme challenges due to its high radiation and electrostatic discharge (ESD) levels and ultra-low temperatures. In addition to such harsh environment conditions, there may be tight volume constraints forcing the antenna to be completely flat and limiting its size. To withstand the harsh temperature conditions and radiation levels, the antenna should be made mainly of metal.
The maximum aperture area for the antenna may be limited, due, for example, to its disposition on Landers and/or Rovers, and therefore, a very high efficiency (e.g. >80%) antenna may be required to close the link from, for example, Jupiter's moons. Several antennas, such as radial line slot antennas (RLSA) (e.g. see Ref [2]) and meta-surface antennas (e.g. see Refs. [3] and [4], have been considered but found not to meet the high efficiency requirements at both uplink and downlink frequencies. Researchers have investigated different approaches to obtain dual-band or wideband performance in circularly polarized (CP) patch antennas, including stacked patch antennas, slotted patch shapes, slotted ground planes, E-shaped, U-slot, L-shaped, and so on (e.g. see Refs. [5]-[9]). None of such approaches were found to be compatible with an all-metal solution that could potentially be scaled to a very large array.
Europa Lander (e.g. see Ref [1]) is a proposed NASA astrobiology concept mission for a lander to Europa, a moon of Jupiter which is thought to have a liquid ocean under its icy surface as well as water plumes. If selected and developed, the Europa Lander Mission may be launched soon to complement the science undertaken by the Europa Clipper mission. The objectives of the Europa Lander mission may be to search for biosignatures at the subsurface, to characterize the composition of non-ice near-subsurface material, and to determine the proximity of liquid water and recently erupted material near the lander's location. It is found that enabling DTE/DFE telecommunication links may substantially reduce the cost of the mission (e.g. from $4.5 B to $2.2B), as no carrier spacecraft with relay capabilities may be required.
Based on the above, there may be a need for an antenna to satisfy, for example, the dual-band communication link with NASA's Deep Space Network at the X-band frequency spectrum for future missions. Applicants of the present disclosure have established that such antenna may provide performance/design parameters that may include: i) meeting of stringent requirements across both uplink and downlink frequency bands with a sufficient thermal guard band; ii) a circularly polarized configuration; iii) an efficiency of higher than 80% at both frequency bands to provide at least a gain of 36.0 dBi (decibels-isotropic) and 37.1 dBi at 7.19 GHz and 8.425 GHz, respectively; iv) an axial ratio of the antenna of better than 3 dB; v) a return loss of the antenna to remain above 14 dB; vi) operation at temperatures down to 50K (˜−223° C.) and high radiation levels; vii) being immune from electrostatic discharge (ESD); viii) handling of an input power of 100 W continuous wave in vacuum; and ix) a flat configuration and fit in a confined volume of, for example, 82.5×82.5×3 cm{circumflex over ( )}3. It should also be noted that the antenna pointing to Earth in azimuth and elevation may be enabled by a mechanical gimbal known per se.
Accordingly, teachings according to the present disclosure describe an all-metal single patch element that can be used in a patch array to provide, for example, a high-efficiency dual-band or wide-band circularly-polarized antenna for telecommunication in harsh environment that satisfy the above performance/design parameters.